I agree with Gemy. There are arguments to be made for neutering early -- prevents additional breeding, which is good for many reasons.
However, for my doggies, I would want to wait until at least 6 months. Teddy was neutered at 7 months and I think even the additional month was beneficial for him.
Gail has posted a lot of info about neutering and health here on YT and can explain better than I can about the maturation process and hormones. While I strongly advocate neutering for pets, I do think there is a health benefit to waiting until the dog is more fully developed. I rushed Max in at 6 months because I feared he would establish the habit of marking in the house if I didn't neuter early . . . and I was tired of people asking me if I wanted to breed him with their dog.
